Underwater diving equipment typically includes a breathing regulator that is connected via a hose to a SCUBA (Self Contained Underwater Breathing Apparatus) air tank or a surface supplied air umbilical. Underwater diving equipment comes in a variety of configurations including FFMs (Full Face Masks), diving helmets, SCUBA and/or the like. A wide variety of underwater diving helmets and FFMs has been used over the years. In the beginning, diving helmets were configured basically as upside down buckets that had look-out windows and an air supply hose connected to it that supplied air from the surface to the diver. As time progressed, these helmets became more advanced and the physics of diving better understood.
Modern day diving helmets have been improved in many ways with features like, being able to be connected to a dry suit or the inclusion of a neck dam to keep the water out and the inside of the helmet, most of the time, dry. New breathing systems have been designed including emergency or alternate air sources, and electronic communications have been added, just to name a few.
One problem with the older diving helmets (commonly known as “heavy gear”) is that the CO2 that is expired by the diver can build up in the helmet causing a potentially dangerous situation for the diver. Air consumption is another concern. These “heavy gear” diving helmets are essentially free flow helmets, i.e. air is constantly flowing through the helmet to “flush” the CO2 out of the helmet. In these types of helmets, the air flow rates need to be quite high which results in consumption of a great deal of air to maintain a safe CO2 level.
In modern day diving helmets or FFMs, these problems have been solved by using what is commonly known as an “oral nasal” mask. The oral nasal mask is a relatively small rubber mask that is installed on the inside of the diving helmet or FFM to seal against the face of the diver covering his/her nose and mouth. The purpose of the oral nasal mask is to direct the flow of exhaust gases out of the helmet or FFM keeping the CO2 levels within the helmet or FFM to a minimum.
Nowadays, to conserve air, most diving helmets or FFMs use what is called a “demand regulator.” This is a breathing regulator, similar to a SCUBA diving regulator, which can be mounted onto a diving helmet or FFM. The demand regulator has a rubber diaphragm that collapses inward with each breath opening a small valve that supplies the diver with air on demand. This small valve is designed to turn off when the diver is exhaling or holding his/her breath conserving the amount of air being consumed by the diver.
The oral nasal mask itself has gone through an evolution. When oral nasal masks were first used, many masks had one or more apertures in the bottom area of the mask that would allow water that had sometimes leaked into the helmet or FFM to pass through to the interior of the oral nasal mask and ultimately be expelled out of the exhaust port of the breathing regulator. In this regard, FIG. 1 schematically shows an aperture 10 in the bottom area of a conventional oral nasal mask 12 covering the mouth and nose of a user 14. Oral nasal mask 12 is disposed within a diving helmet 16, and is operatively coupled to a breathing regulator 18. Helmet water is dumped via aperture 10 and the exhaust port of breathing regulator 18. Helmet water is excess water that may have accumulated in the bottom portion of the helmet. It was later learned that the provision of such aperture(s) was beneficial only when a small amount of water was left over in the bottom of the oral nasal mask. This left over water was instrumental in blocking the exhaust gases from escaping the oral nasal mask via the aperture(s) and contaminating the inside of the diving helmet during exhalation.
Another oral nasal mask configuration, and currently the most commonly used, is one that has a rubber mushroom-type valve installed in the upper portion of the oral nasal mask. A mushroom-type valve is a one-way valve that has a diaphragm resembling a mushroom. The mushroom-type valve in the upper portion of the oral nasal mask is oriented such that the air is allowed to flow from inside the helmet to the interior of the oral nasal mask. A rubber mushroom-type valve 20 disposed within the upper portion of an oral nasal mask 22 is schematically shown, for example, in FIG. 2. Oral nasal mask 22 covers the mouth and nose of a user 24. Oral nasal mask 22 is disposed within a diving helmet 26, and is operatively coupled to a breathing regulator 28. Helmet water is dumped via an additional rubber mushroom-type valve 30 bypassing the exhaust port of breathing regulator 28. Rubber mushroom-type valve 30 is provided in the lower portion of diving helmet 26 (FIG. 2). Helmet water is dumped directly into the surrounding water via mushroom-type valve 30, as shown by directional arrow 32 in FIG. 2.
Most helmets and FFMs presently are equipped with an emergency or alternate air source which is usually controlled by the diver turning a valve that is mounted either to the side of the helmet or FFM or is mounted to the divers harness. When used properly, the alternate air enters the side of the helmet or FFM, as shown, for example, in reference to FIGS. 1-2. For example in FIG. 2, alternate air within helmet 26 enters oral nasal mask 22 via rubber mushroom valve 20. The incoming alternate air within helmet 26 forces excess water built up inside helmet 26 out into the surrounding water via mushroom-type valve 30 (FIG. 2).